diff --git a/web/colormapping.go b/web/colormapping.go
index 476239c..4cd8c6f 100644
--- a/web/colormapping.go
+++ b/web/colormapping.go
@@ -9,6 +9,7 @@ type Color struct {
 	R uint8 `json:"r"`
 	G uint8 `json:"g"`
 	B uint8 `json:"b"`
+	A uint8 `json:"a"`
 }
 
 func (api *Api) GetColorMapping(resp http.ResponseWriter, req *http.Request) {
@@ -16,7 +17,7 @@ func (api *Api) GetColorMapping(resp http.ResponseWriter, req *http.Request) {
 	cm := make(map[string]Color)
 
 	for k, v := range api.Context.Colormapping.GetColors() {
-		cm[k] = Color{R: v.R, G: v.G, B: v.B}
+		cm[k] = Color{R: v.R, G: v.G, B: v.B, A: v.A}
 	}
 
 	resp.Header().Add("content-type", "application/json")